Endoscopes are commonly used in the medical field for providing access to body cavities with decreased invasiveness. Rigid endoscopes include a rigid insertion tube, while flexible endoscopes typically include a flexible insertion tube. The insertion tubes, which extend from a hand piece or control portion, are configured to be inserted into a body cavity. A distal tip of the insertion tube includes an array of peripherals for providing various functions. For example, the distal tip may include lighting for illuminating the body cavity, one or more ports for delivering air or irrigation, suction ports for removing debris from the body cavity, a medical device or tool, and optics for providing a view of the body cavity to an operator of the endoscope.
Endoscopic systems may include one or more image sensors to provide the surgeon with a video image of the procedure. In some instances, the image sensor may be configured to process electromagnetic radiation in the visible spectrum as well as the infrared spectrum to provide a white light video and/or a fluoroscopic video. In such systems, complementary metal oxide semiconductor (CMOS) sensors are commonly employed in endoscopes due to their ability to provide reduced readout times and faster frame rates. For instance, CMOS may capture up to 60 frames per second.
The image sensor includes a plurality of pixels arranged in a matrix having X number of rows and Y number of columns. The image sensor scans the electromagnetic radiation collected in each row successively to produce an image frame. Upon reaching the last row, the image sensor scans the first row to begin the process of producing another image frame. The speed at which the image sensor scans the pixel matrix to produce a frame is commonly known as, and referenced herein as the “frame rate.” The image sensor operates at a predetermined rate.
The camera control unit then compiles each image frame processed using electromagnetic radiation in the visible spectrum to generate a white light video image. Each image frame processed using electromagnetic radiation in the infrared spectrum is also compiled to generate a fluoroscopic video image.
By properly timing the switching of light sources so that the image is illuminated with electromagnetic radiation in the visible spectrum when a white light image frame is exposing, and with electromagnetic radiation in the infrared spectrum when a fluorescent light image frame is exposing, white light and infrared images can be captured in sequential or alternate frames. Inconsistent or mistimed switching may result in insufficient light, incorrect light, or an undesired mixing of light during the exposure of either the white light image frame or the fluorescent light image frame.
Environmental factors such as heat, may affect the operation of the light source, which may cause a phase shift in the timing of the light source switching. For instance, the light source may be turned on after the image sensor begins a new scan of the pixel matrix and only the third or fourth rows are able to collect electromagnetic radiation for image processing. As such, the images may not be fully exposed or uniformly exposed with the correct spectrum of light within a corresponding frame. Such frames may be discarded from video compilation that may lead to an imperfection in the video image.
However, synchronization of the light source with the operation of the image sensor is not needed in all cases. For instance, the imaging system may begin with the image sensor and the light source synchronized with each other. After a period of time, the phase of the light source may be delayed due to timing drift, or changes in circuit delays as a result of temperature.
The actuation of the synchronization unit may increase the processing demands of the imaging system. The imaging system performs other computing functions that also increase processing demands and as such, the processing demands may overload the computing capabilities of the imaging system. For instance, the imaging system performs image processing, data recording and storing, data processing and the like which may affect the performance of the imaging system.
Accordingly, it remains desirable to have an imaging system wherein the synchronization between the light source and the image sensor is adjustable so as to reduce processing demand required to synchronize the light source and the image sensor.